Dental tool



Aug. 4, 1931. D. D. LEVY DENTAL Tool. Filed .my 7. 192s Patented Aug. 4, 1931 UNITED STATES PATENT vllUDLfElY D. LEVY, F .NEW YORK, Y., ASSIGNORTO DUDLEY yRESEARCH .CORPOKRA TIGN; 0F NEW .YY0RK, N. Y., A CORPORATION 0F NEW'YORK l DENTAL Toor,

Application lled A@Tilly v'?, 1928. Serialf'Nm :290,920;

lo hammer and meansfor reciprocating said hammer to thereby' impart a succession lof rapid h-ammer fblows to 'a tool o r to'ol holding head. v

A further object is the provision of means whereby the hammer is brought into action only by pressure on the tool. 1

*Qther 'objects wilflappear herein-after and I obtain these objects by .the 'construction illustrated Iin the accompanying fdrawings in H which- Figure l'isaview showing :my device .rattached to a drive pulley and holden;

Fig.'2 yisa View partly'in fsection'ta'ken .on the linel2-2`of Fig. 1,; 1

Fig. 3 [is a View similar to Fig. 2, but showing the hammer tensioned and ready to descend upon the tool head; and

Fig. 4 is a detailed view of the pawl and tripping mechanism.

Like numerals refer to similar parts throughout the severalviews.

In a preferred form of construction I pro-y vide a shell or casing 10, of suitable dimensions, wherein is contained my improved and new assembly. The tool carrying end of said shell engages a threaded hollow member 11 within which is reciprocally held the tool holding member 12 by a pin 13," or its equivalent, extending into slot 14 in the neck 15 of- Y said tool holding member. Neck 15 is threaded internally and is designed to receive a tool 16, which may be a chisel, or other tool suited for the work at hand.

The tool holding member 12 has an enlarged head to receive the hammer blows of the hammer 17 as it reciprocates on the angular drive shaft 18 in the manner about to be described. Shaft 18 has a round tip 20 to ro tatively and reciprocally fit into the plain bore of the tool holding member 12. This member lis held againstrotati'on pin 13engauging-slot 14. VThe upper end '23 of drive shaft'18 is provided with-a washer 24 welded vor otherwise fastenedzonthe shaft andagainst which Ya'buts 'spring 25 fon the one lsideand fthe assembling nut 526 onth'e other. lhe "drive end y28 of1-shaft`1=`8 .may :be .tapered 'andV is designed -to receivetheengaging member (not sh'oiwnl) v'of the driven shaft `27 which -carries pulley 28 or its equivalent.' The driven shaft and -theengaging member are 'carried' in a suitable housing 29 'of known construction andthefe-nd olf 'the housing frictionally l.fits 'on theextenson of nut 26, y v

V'It willbe' noted that fhammer 17 is provided with, aca'vity vto receive 'aperti-on -fo'f spring 25. Said hammer I*is also provided exteriorly with Va rather coarse screw 'thread L30., which begins with a shallow portion 31 y:and ends in @b1-ind thread and smooth-head e2. A

pawl lh-avin'ga downwardly curved ltail 84 `is Ypivotally mountedfin exterior lugs 35. A spring 86 de presses the tail -34 to engage the fscrew 'thread 30 yunder conditions stated below. p Y

` "The'headend .37 of paw-l 33 is beveled and normallyvengages tlie-seat88of'=the Epawl `controlling slide head 140 of slide member 41. This member ils slidabl'y held cleat 42 on whichis located the spring .anchoring pin v 43.4 y.A 'pin '45 is fastened inislide member 41 ali-idseirtfes` for holding vthe 4other end of the slide lten-sioninfgspring 44. The pin itself is mounted to move longitudinally in the `shell slo't` 46 and spring 44 ltensions pin 45 Vand its slidetew'alrds Sthe pawl83. From .this 'const-ructionlit -ifs lapparent that the tension yof spr/ing i434 lifts pawl 34 out of .engagement with threadsBO .by a wedging action.

In Fig. 2 pawl 38 is shown :in engaging or locked position, that is the tail 34 is Ein xengafgement with ith'e screw thread 30 :of `hammer v'17 #andthe-'head fend 37 engages seat 38ofthefslidemember L41. By reason ,of the rotation of thehammenas shown by the arrow, said hammer iis ftensioned against spring 251intoith'e position shown in Fig. 8. The .instant that tail '84 reaches @the .blind thread `50 on. :h'ea'd TS2-it .is tripped fto fdisengage v:the mouth '88 ofllslide 41 which isf-then moved into open position by spring 44,. Because tail 34 is lifted above threads 30 the hammer is released to strike the head of the tool holding member 12, thereby imparting a sharp blow to said member and its tool, the force of which is dependent on the intensity of spring 25. The spring is removable and a spring of different intensity may be used suited for the work that is to be done.

As the hammer strikes member 12 and moves it a short distance outwards, said member also strikes the trip lug 21 and there by moves the lug and its pin, together with slide 41, to the closed position shown in Fig. 2. The tail 34 of trip 33 is then again depressed, but since the hammer is moved forward the tail lies outside of the thread end 31. When in this position the hammer will rotate idly without being wound up. The

moment, however, that pressure is applied tothe tool and the tool *holding head is pressed inward against the hammer so as to move it also a short distance inwards, tail 34 will engage threads 30 to repeat the action just described.

It is obvious that the number'of hammer blows per unit of time is dependent upon therevolutions of the hammer -andits drive unit. In the construction from which the illustrative drawings herein are made, I obtained 120 hammer blows per minute at 3000 R. P. M. for its most efficient operation. The speed, however, may be varied within wide ranges.

Having now described my invention, what I claim as new and useful and desire to secure by Letters Patent is 1. In a device of the class described, the combination with a casing, of a tool holding member mounted in said casing, said member Ihaving a head,I a drive shaft rotatively mounted in said casing and extending substantially the length thereof, said shaft in free engagement with the head of said tool holding member, a hammer member mounted to reciprocate on said shaft, a spring on said shaft for forcing said hammer member into contact with the head of said tool holding member, means including a pivotally supported pawl for engaging said hammer member to force it against said spring, and means for temporarily releasing said hammer engaging means to thereby impart a rapid succession of blows on the head of the tool holding member.

Q. In a dental tool, a hammer rotativ'ely mounted and having screw threads thereon and tensioning means therein, means for engaging said threads, means for rotating said hammer to thereby move said rotating hammer longitudinally against said tensioning means, means for releasing said thread engaging means, and means to again cause said thread engaging means to become effective.

3. In a dental tool, a hammer rotatively mounted and having screw threads thereon and a cavity therein, a spring carried in said cavity and extending therefrom, a pawl for engaging said screw threads, a drive shaft on which the hammer is adapted to move against said spring as it is rotated, means for holding said pawl in engagement with the screw threads, and means for temporarily holding said pawl in disengaged position.

4L. In a dental tool, a hammer having screw threads thereon, and said threads terminating blindly in the hammer head, a pawl mounted to engage said threads to move the hammer longitudinally as it is rotated against tensioning means, said pawl being lifted 'out of the thread engaging position by the blind thread, a slidable catch member tensioned to engage the pawl to hold said pawl in lifted position to permit the hammer to be moved by the energy of said tensioning means whereby said pawl holding means is moved to release said pawl for reengagement with the screw thread.

5. In a device of the class described, the combination with a casing, of a tool holding member mounted in said casing, means for holding said tool holding member against rotation, an angular drive shaft mounted to rotate in said casing, said shaft having a round tip to engage said tool holding member, a hammer mounted on said drive shaft to rotate therewith, means for reciprocating said hammer member on said shaft to impart hammer blows on said tool holding member,

, and means to render said reciprocating means effective by applying pressure to the tool holding member.

: In testimony whereof I have hereunto set my hand on this 3rd day of July, A. D. 1928. i DUDLEY D. LEVY. 

